Cardiovascular system

Question 1

Functions of the CVS - 3

Answer 1

1. Deliver nutrients and oxygen
2. Remove CO2 and waste
3. Regulate body temperature

Question 2

What is the role of the heart

Answer 2

To create pressure difference to drive blood flow

Question 3

What is the percentage of RBC in blood and what is it also referred to as?

Answer 3

42%
Hematocrite

Question 4

Why is blood pressure lowest in the capillary sphincters?

Answer 4

Allows for greater nutrient exchange with skeletal muscle

Question 5

What is total peripheral resistance?

Answer 5

The sum of all resistances to blood flow in peripheral organsD

Question 6

Describe the relationship between blood flow, pressure and resistance

What equation describes this relationship

Answer 6

Blood flow directly proportional to pressure
But, indirectly proportional to resistance

Darcy = change in pressure / resistance = flow

Question 7

Give the resistance equation
What factors influence resistance

Answer 7

Resistance = length x velocity / radius4
- length
- viscosity
- diameter

Question 8

What is a-vO2

Answer 8

Ateriovenous difference is the uptake of O2 from 100ml blood

Question 9

What equation relates VO2 and a-vO2?

Answer 9

Fick’s equation
VO2 = Q x a-vO2

Question 10

What does central command theory suggest in terms of the cardiovascular system

Answer 10

Initial drive for the CV comes from higher brain centre, which is later fine tuned by mechanoreceptors, chemoreceptors and baroreceptors

Question 11

What is the exercise pressor reflex

Answer 11

peripheral sends feedback to the medulla oblongata to amend CV response to exercise

Question 12

What is the baroreflex? What happens in exercise?

Answer 12

Negative feedback loop concerning BP
During exercise it is reset - to ensure adequate uptake of oxygen

Question 13

From the outer most layer in - name the hearts structural layers

Answer 13

1. Epicardium
2. Myocardium
3. Endocardium

Question 14

Name 4 differences between skeletal muscle and cardiac muscle

Answer 14

1. Heart is involuntary
2. Single nuclei
3. No satellite cells - no regeneration
4. Intercalated discs

Question 15

Describe the cardiac electrical activity

Answer 15

1. SA generates AP
2. AP spreads across atria
3. AV delays in firing - due to small number of intercalated discs
4. AP moves into interventricular septum and down the bundle branches
5. AP moves through Purkinje fibres, ready for ventricular contraction

Question 16

Describe an ECG trace

Answer 16

P wave - atrial depolarisation
QRS - ventricular depolarisation
T wave - ventricular repolarisation

Question 17

What does Q increase to during exercise?

Answer 17

From 5 to 25L